1. Field of the Invention
The present invention relates to a grease composition having improved load-carrying properties and a method of its preparation.
2. Description of Related Art
The use of polyhydric alcohols such as glycerol as a grease additive is known. For example, U.S. Pat. No. 2,858,273 (the disclosure of which is incorporated herein by reference) discloses incorporating a polyhydric alcohol, a metal organo-dithiocarbamate and an alkanol amine into calcium soap greases to impart extreme pressure properties. Patentee teaches that the alkanol amine is essential to provide good mechanical stability. He further teaches that alcohols containing 2 to 4 hydroxyl groups are operative in his compositions.
As another exmample, U.S. Pat. No. 3,133,020 (the disclosure of which is incorporated herein by reference) discloses a lithium based grease having improved extreme pressure properties due to the incorporation therein of an aliphatic polyhydric alcohol and a metal organodithiocarbamate.
However, none of the prior art references teach or suggest that the load-carrying capability of a grease composition can be significantly improved by incorporating therein the particular combination of additives claimed herein.